/*
 * Copyright (C) 2014 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.gson.internal.bind;

import com.google.gson.*;
import com.google.gson.annotations.JsonAdapter;
import com.google.gson.internal.ConstructorConstructor;
import com.google.gson.reflect.TypeToken;

/**
 * Given a type T, looks for the annotation {@link JsonAdapter} and uses an instance of the
 * specified class as the default type adapter.
 *
 * @since 2.3
 */
public final class JsonAdapterAnnotationTypeAdapterFactory implements TypeAdapterFactory {
    private final ConstructorConstructor constructorConstructor;

    public JsonAdapterAnnotationTypeAdapterFactory(ConstructorConstructor constructorConstructor) {
        this.constructorConstructor = constructorConstructor;
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> targetType) {
        Class<? super T> rawType = targetType.getRawType();
        JsonAdapter annotation = rawType.getAnnotation(JsonAdapter.class);
        if (annotation == null) {
            return null;
        }
        return (TypeAdapter<T>) getTypeAdapter(constructorConstructor, gson, targetType, annotation);
    }

    @SuppressWarnings({"unchecked", "rawtypes"})
        // Casts guarded by conditionals.
    TypeAdapter<?> getTypeAdapter(ConstructorConstructor constructorConstructor, Gson gson,
                                  TypeToken<?> type, JsonAdapter annotation) {
        Object instance = constructorConstructor.get(TypeToken.get(annotation.value())).construct();

        TypeAdapter<?> typeAdapter;
        if (instance instanceof TypeAdapter) {
            typeAdapter = (TypeAdapter<?>) instance;
        } else if (instance instanceof TypeAdapterFactory) {
            typeAdapter = ((TypeAdapterFactory) instance).create(gson, type);
        } else if (instance instanceof JsonSerializer || instance instanceof JsonDeserializer) {
            JsonSerializer<?> serializer = instance instanceof JsonSerializer
                    ? (JsonSerializer) instance
                    : null;
            JsonDeserializer<?> deserializer = instance instanceof JsonDeserializer
                    ? (JsonDeserializer) instance
                    : null;
            typeAdapter = new TreeTypeAdapter(serializer, deserializer, gson, type, null);
        } else {
            throw new IllegalArgumentException(
                    "@JsonAdapter value must be TypeAdapter, TypeAdapterFactory, "
                            + "JsonSerializer or JsonDeserializer reference.");
        }

        if (typeAdapter != null) {
            typeAdapter = typeAdapter.nullSafe();
        }

        return typeAdapter;
    }
}
